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authorAlexei Starovoitov <ast@kernel.org>2020-01-31 16:03:14 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2020-02-04 00:06:07 +0100
commit257af63d7f84f0672aa6a24b5511871f00741f19 (patch)
tree2f7453642cf117d0550a4af58b15a1ae312d1139 /kernel/bpf
parenta525b0881de7742617343f02df4073ddc1571237 (diff)
bpf: Fix modifier skipping logic
Fix the way modifiers are skipped while walking pointers. Otherwise second level dereferences of 'const struct foo *' will be rejected by the verifier. Fixes: 9e15db66136a ("bpf: Implement accurate raw_tp context access via BTF") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200201000314.261392-1-ast@kernel.org
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/btf.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 8c9d8f266bef..805c43b083e9 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3931,6 +3931,7 @@ again:
if (btf_type_is_ptr(mtype)) {
const struct btf_type *stype;
+ u32 id;
if (msize != size || off != moff) {
bpf_log(log,
@@ -3939,12 +3940,9 @@ again:
return -EACCES;
}
- stype = btf_type_by_id(btf_vmlinux, mtype->type);
- /* skip modifiers */
- while (btf_type_is_modifier(stype))
- stype = btf_type_by_id(btf_vmlinux, stype->type);
+ stype = btf_type_skip_modifiers(btf_vmlinux, mtype->type, &id);
if (btf_type_is_struct(stype)) {
- *next_btf_id = mtype->type;
+ *next_btf_id = id;
return PTR_TO_BTF_ID;
}
}